Pressure ulcers – also known as bedsores – pose a considerable economic burden to the UK’s NHS and the global healthcare system as a whole. In the UK, approximately 10% of inpatients suffer from pressure-induced ulcers in hospital settings, costing £2.1 billion a year.

Bedsores are areas of localised damage to the skin and underlying tissue – usually over bony areas such as the coccyx and sacrum – as a result of pressure with shear and/or friction. Blood vessels become obstructed, which reduces the supply of nutrients to cells and causes an increase in the accumulation of toxins in the local area. This can lead to hypoxia, apoptotic or necrotic events and tissue damage. Pressure ulcers occur in people who are bedridden or confined to a wheelchair, often quickly, and are painful and uncomfortable for patients. They can also result in patients requiring an extended stay in hospital, averaging between an extra six to ten days a patient.

Detection and assessment

“The wounds range in severity from superficial tissue damage to full-scale tissue destruction,” says Zena Moore, professor and head of the School of Nursing and Midwifery at the Royal College of Surgeons in Ireland. “Pressure ulcers occur most often in individuals who have activity or mobility problems and are exposed to prolonged periods of exposure to sustained pressure/shear forces.

“Prevalence rates range from 8.8% to 53.2% and incidence rates vary from 7.0% to 71.6% across Europe, the US and Canada. Furthermore, 72.0% of all pressure ulcers occur in the over-65 age group and, worryingly, global mortality directly attributable to pressure ulcers increased by 32.7% between 2000 and 2014.”

Detecting pressure ulcers relies on nurses visually inspecting patients’ skin, and turning them in their beds every few hours to allow oxygen to reach the area and the blood supply to move freely again. It also relies on risk assessment scales that judge which patients are most at risk; these scales are subjective and rely on the skill and expertise of the nurse.

Current practices, which focus solely on the appearance of the skin, miss the opportunity for early detection and intervention that can prevent pressure ulcers, as physiological changes take place below the skin three to ten days before they appear on the surface. As a result, treatments are often offered to patients who don’t need them and not offered to those who do. Evidence has shown that pressure ulcer damage is reversible if identified early and interventions put into place.

“Currently, pressure ulcer development is assessed using visual assessment, which only allows the person to see when changes occur on the surface of the skin,” says Moore. “We know that many pressure ulcers develop within the deeper layers of the tissues, at the bone and muscle border, and emerge outwards to the surface of the skin. Because we cannot see this damage until it has already extended from the deep layers to the skin surface, prevention is made more challenging.

“However, because fluid accumulates beneath the skin when damage is beginning to happen, and this is the first early sign of a pressure ulcer developing, we need a device that enables us to detect this early damage. Knowing that it’s there would mean that we could increase prevention measures, such as moving the patient more, and therefore reduce the likelihood of a worsening pressure ulcer developing.”

The biometric scanner

Such a device has been developed and is currently being trialled in hospitals around the world. The new handheld biometric scanner is capable of objectively and reliably detecting an ulcer three to ten days before visible signs appear, effectively eliminating the guesswork involved in diagnosis. The scanner was conceived by Barbara Bates-Jensen, a wound care expert and professor of nursing and medicine at the University of California. With the aid of her university’s engineering and computer science departments, she adapted seismology technology taken from NASA’s Mars landing craft to create a prototype scanner, which was then taken forward by medical technology company Bruin Biometrics.

The scanner can spot changes in sub-epidermal moisture (SEM) – a biophysical marker associated with oedema and tissue fluid in the inflammatory phase of pressure-ulcer formation. SEM is the body’s first response to tissue damage, which occurs as the blood and lymph vessels become blocked, and waste products accumulate in the cell niche
and interstitial space. The SEM scanner can evaluate changes in SEM by simply being placed on the areas most prone to bedsores to assess tissue damage.

“The SEM scanner is a simple, non-invasive, handheld diagnostic tool for the identification of early-stage pressure ulcers,” explains Moore. “It uses bioimpedance technology to assess changes in moisture in the tissue, which fluctuates upon damage and throughout the wound healing process. The SEM scanner detects these changes beneath the surface of the skin using an integrated electrode sensor. It works by measuring skin surface electrical capacitance (the ability of the body to store electrical charge), which is determined by the impedance (the effective resistance) of the skin to electrical forces.”

Bioimpedance techniques offer a painless and harmless way of acquiring data from human subjects, and have previously been used to monitor changes in the respiratory and cardiovascular systems, the brain and the distribution of fluids in the body following events such as surgery or conditions like lymphedema. Bioimpedance varies by cell and tissue/organ type and, therefore, also by anatomical site and from person to person.

Clinical studies

Clinical studies focusing on bioimpedance for detecting ulcers suggest that changes in the electrical properties of the skin correlate with increasing severity of pressure ulcer stages, while other studies have shown that at anatomical locations with pressure ulcers, bioimpedance varies with the distance from the centre of the pressure ulcer.

Results from a recent study conducted by the Royal College of Surgeons in the Republic of Ireland, for which Moore was principal investigator, showed that the scanner detected tissue damage more quickly and reliably than the current visual assessment method. Full results from the study are yet to be published, but an abstract has already been presented to the European Pressure Ulcer Advisory Panel and, in 2016, to the Wound Management Association.

The team followed 47 patients – 29 women and 18 men, with a median age of 74.7 years – on an acute care ward for four weeks, starting from the time at which patients were assessed as being at risk of a pressure ulcer. Data collected included nurses’ documented skin assessments, and researcher-led SEM measurements over the sacrum and both heels of the patients. In 34% of patients, SEM readings remained elevated over the study period and all 16 patients went on to develop signs of pressure ulcer damage. The mean number of days for nurses to detect the damage was 5.0, while it took 1.1 days for the SEM scanner to spot injury – on average, 3.9 days earlier than the nurses’ assessment.

The scanner can be invaluable in giving a heads up about the possibility of patients developing pressure ulcers, offering real-time readings to indicate if an ulcer is forming. Early detection can lead to improved patient outcomes, targeted intervention, lower incidence of pressure ulcers, earlier recovery and a lower cost of care.

The cost of treating a pressure ulcer rises dramatically once the skin is broken, and it is suggested that the treatment of a pressure ulcer costs approximately two and a half times more than prevention. However, figures estimate that its costs up to £75 a patient a day to prevent an ulcer forming, while it could cost up to £400 a patient a day to treat it.

“The amount of money spent on treating pressure ulcers is a concern, as most pressure ulcers can be avoided with appropriate risk assessment and use of interventions targeted at combatting this risk,” says Moore. “However, despite this, it is estimated that approximately 4% of the annual healthcare budget in Europe is being spent on pressure ulcers, with nursing time accounting for 41% of these costs. Pressure ulcers have also been shown to increase length of hospital stay, readmission and mortality rates. Therefore if we could recognise the early development of a pressure ulcer before it becomes too serious, and then put in good interventions to prevent worsening of the pressure ulcer, we could save a lot of money, and, more importantly, increase the comfort and quality of life of patients.”

Positive outlook for patients

Not only are ulcers physically painful, but they can also impact emotional, mental and social aspects of a patient’s quality of life; negative effects can come from pain, malodour and simply by the appearance of the ulcer.

“Pressure ulcers have a large impact on those affected; the wounds may become seriously infected and can be foul-smelling,” says Moore. “Pain is one of the most commonly cited complaints, and, worryingly, this pain is often continuous and is made worse by some of the treatments employed to manage the wound. People with pressure ulcers have a significantly lower health-related quality of life than those without.”

Not only could this simple handheld device revolutionise the way pressure ulcers are prevented in susceptible patients, but it could also save hospitals money and nursing time, and help free up hospital beds currently being used by those unfortunate enough to have developed an ulcer. For patients, the advantages are also clear: they are less likely to develop a pressure ulcer and, if they do, targeted treatment can be offered far sooner than is possible with current monitoring methods.